The only credible claim that you can make, based upon your alleged facts is an age discrimination claim. That is, whatever the purported reason for your termination may be, the fact that there is no evidence of your poor performance, the true reason for the termination is that you're age makes you a less desirable employee, because you earn more than someone younger who could be hired to replace you for less.
The fact that the other employee is being terminated as a means of pretending that the entire department is being eliminated, adds to the evidence of age discrimination, because the department was actually earning money (and, no rationale business would close a department that's profitable -- so, there must be another reason.
I can't promise you that you can actually prevail on an age discrimination claim. However, if you were to "mention" that you can't understand the rationale for eliminating a profitable department, and that it seems like a pretext for something else -- maybe the employer will rethink its strategy.
If not, then your only recourse is to file a complaint with the Department of Fair Employment and Housing
(DFEH) -- or, hire a private employment rights lawyer
and sue for age discrimination.
Hope this helps.
NOTICE: My goal here is to entertain while educating the public about the law. Your positive feedback to the website is appreciated. If you need to contact me again, please put my user id at the beginning of your question ("To Socrateaser"), and the system will send me an alert. Please Click the following link for IMPORTANT LEGAL INFORMATION
. Thanks and best wishes!